This invention relates generally to educational devices and in particular to devices for teaching pre-school and elementary school children solutions to problems involving two known facts.
The educational devices of the prior art that were used to teach solutions to arithmetic problems all utilized a rectangular display of either loose blocks or cards and a playing board or rack onto which the blocks or cards were placed to designate solutions to arithmetic problems displayed along an outer edge of the playing board. For example, one device used a tray with numbers disposed along a vertical and horizontal edge and a plurality of numbered blocks which are placed at the horizontal and vertical coordinate intersections to correspond to the product of the respective numbers along the horizontal and vertical edges.
Some devices used rectangular blocks with various types of slotted edges to permit interlocking the blocks. Still others used not only rectangular six sided blocks but also blocks having eight or more sides with indicia on each side or flat surface.
One device used a plurality of disks disposed in a rectangular array and pivotally mounted in rows on parallel spaced apart rods.
All the prior art devices required the use of many loose and easily lost playing pieces or complicated mechanical arrangements that were costly to manufacture.